The invention relates to a microscope having an objective, a binocular unit and an optical path system for erecting the image, this optical path system comprising first and second optical components for deflecting the light beam and an optical bridge between the exit optical axis of the first optical component and the entry optical axis of the second optical component. The axes are parallel to one another and, starting from the normal initial positions of the components abut their respective axes, relative to the optical bridge, the angle of the first optical component about its exist optical axis is equal to the angle of the second optical component about its entry optical axis, but in the opposite sense to this angle, while in addition the entry optical axis of the first optical component coincides with the optical axis of the microscope objective.
A microscope of the foregoing type has, for example, been disclosed in German Offenlegungsschrift No. 2,502,209. In this microscope, the binocular unit can be pivoted in order to alter the viewing angle, to which end the optical components are rotatable about their respective axes. These optical components take the form of half-cube prisms and are aligned, in their normal initial positions, such that the entry optical axis of the first optical components is collinear with the exit optical axis of the second optical component, but counter to this axis, and the optical bridge is composed of a half-cube prism and a pentagonal prism of the roof-edge type, so that the image is rotated once through 180.degree.. By this means, the observer does not see the observed object upside-down and the image is prevented from rotating when the binocular unit is pivoted, so that the orientation of the displacement of the image which is observed in the microscope is the same as the orientation of the manipulations performed on the object. As a result, it is comfortable to work with a microscope of this type.
The known microscope is of the stereoscopic type, in which each of the two stereo optical paths is provided with its own erecting path system, each of which is adjoined by an eyepiece tube. The intereyepiece distance is adjusted to match eye-spacing in the manner of a so-called bent tube, that it to say by swinging the two tubes about a central axis, together with their respective erecting path system and microscope objectives.
If it is desired to achieve image-erection in the case of a conventional microscope, which has not been designed for stereoscopic viewing, and which possesses a binocular unit which divides the single object beam between two optical paths, a problem of space arises. This space problem derives from the fact that the calculated image distance of the object or the focal length of the tube lens predetermines the distance of the plane of the intermediate image from the microscope objective or, when objectives which are corrected for infinity are used, the tube lens which follows the microscope objective. In reality, if the erecting system and the binocular unit are simply placed one behind the other, the latter splitting the optical path into two, the length of the optical path between the microscope objective and the eyepiece becomes so large that, in the case of a simple microscope which is not suitable for stereoscopic viewing but which possesses a binocular unit, the path length can no longer be accommodated.